1. Technical Field
The present invention relates to a stretchable circuit board and strain sensor.
2. Related Art
Development of stretchable electronics using stretchable sheets as stretchable substrates and placing stretchable conducting films and electric circuits on the stretchable substrates is advanced. Such a stretchable substrate is disclosed in Patent Document 1 (JP-2016-143763). According to the patent document, circuit elements and wires are connected by connecting portions. Mixture of an elastomer material and a conducting material is used for the connecting portions. When a tensile force acts on the board, the connecting portions also deform, and thereby, concentration of stress is relaxed.
In Patent Document 1, a covering portion covering terminals of electronic components is provided and a resin material is used for the covering portion. When a tensile force acts on the stretchable substrate, stress within the wires becomes larger on the outer circumference of the covering portion. The wires tend to be broken on the outer circumference of the covering portion. Accordingly, a stretchable circuit board that may suppress division of stretchable conducting films as the wires on the outer circumference of the covering portion is desired.